Creatine increases levels of DHT in the body: https://pubmed.ncbi.nlm.nih.gov/19741313/

DHT appears to drive hair-loss in genetically-predisposed men: https://www.ncbi.nlm.nih.gov/books/NBK278957/

Propecia's mechanism of action to stop/reverse male pattern baldness is to block the conversion of testosterone into DHT: https://www.ncbi.nlm.nih.gov/books/NBK513329/

There is not a proven pathway from creatine to hairloss, but if you are genetically predisposed to male pattern baldness then increasing the amount of DHT in your system via creatine supplementation may contribute to further hair loss insofar as DHT drives hair loss for certain men.

I've experienced this hair loss, and if you read the comments underneath most posts/videos about creatine, you'll find a lot of people chiming in with the same experience. If you don't have male pattern baldness though, seems you're fine.

It is alleged, but not substantiated.